Abstract

Polarization diversity is considered a useful technique in coherent receiver design in order to avoid polarization controllers /1/.One of the optical key components in these systems is the TE-TM polarization splitter. Several guided wave configurations have been proposed and realized using intersecting waveguides /2,3/ or directional couplers /4/. The intersecting waveguides may be operated passivly whereas the directional coupler type polarization splitter requires a DC-tuning voltage for adjusting the TE-crossover.However, in the case of intersecting waveguides, care must be taken in the design of the intersecting region, since a simple Δn-construction /2/ leads to an increased differential loss of both exited modes and, consequently ,to a reduced splitting ratio, whereas the superposition of two titanium stripes to built up the intersection /3/ is sensitive to Δn-asymmetries whith the consequence of increased crosstalk /5/.This paper explores the capability of two-mode-interference (TMI)devices as polarization splitters. The potential of electrooptic tuning in LiNbO₃-devices is discussed and experimental results on passive crossing waveguides with a specially designed intersection region in Ti:LiNbO₃ are presented for λ = 1.3 µm.

© 1988 Optical Society of America